Many selective adrenergic agonists have been shown to act in the central nervous system to reduce blood pressure and heart rate by stimulating selective adrenoceptors. In the art, this type of action has been used as the basis for developing new chemical agents which could be antihypertensive agents. One major concern of this type of compound if they are used as antihypertensive agents is the side effect - sedation. Thus, dissociation of sedative and cardiovascular actions has been a goal in the development of a great many new central acting .alpha..sub.2 -adrenoceptor agonists. A selective adrenergic agonist possessing either hypotensive or sedative action is a precursor for new antihypertensive agent or anesthetic agent, respectively.
The clinical uses of these latter compounds are very limited due to the dual actions: hypotensive and sedative effects, produced by this type of compounds. It is very clear that the development of a selective antihypertensive agent without sedative effect or vice versa would have the potential clinical applications. However, this type of compound is a very useful tool to study the adrenergic receptors subtypes of their pharmacological or anatomical aspect.